The new feature will only be available to a small number of U.S. users who access Facebook on the mobile Web (m.Facebook.com).

The trending section will appear at the top of the News Feed on the mobile site and will generate popular trending topics with and without hashtags. The new feature will rank the topics in a way that allows the user to see the stuff that their friends shared with them first before public posts related to the topic.

Twitter has a similar unit on its desktop and mobile platforms where it makes visible what people are talking about on the network.

This isn't the first time Facebook has tried to mimic Twitter. Mark Zuckerberg's company has introduced searches via hashtags to its platform, like Twitter features, and also recently introduced video to Instagram, which many considered to be a direct rip-off of Twitter's Vine app.